The Heart: Pericardium and Layers Overview

The Heart: Pericardium, Layers and Fibrous Skeleton

• The pericardium is a membrane that surrounds and protects the heart.
• It confines the heart to its position in the mediastinum while allowing freedom for movement during contractions.
• It consists of two parts: the fibrous pericardium and the serous pericardium.
• The fibrous pericardium is a tough, inelastic membrane preventing overstretching and anchoring the heart.
• The fibrous pericardium is partially fused to the diaphragm.
• The serous pericardium is a thinner membrane with an outer parietal layer and inner visceral layer (epicardium).
• The visceral layer (epicardium) is part of the heart wall, adhering tightly to its surface.
• A thin film of pericardial fluid resides between the parietal and visceral layers lubricating movement.

Layers of the Heart

• The heart wall has three layers:
  • Epicardium (outer layer): also known as the visceral layer of the serous pericardium.
  • Myocardium (middle layer): Composed mainly of cardiac muscle tissue, responsible for the pumping action of the heart.
  • Endocardium (inner layer): A thin layer of endothelium that lines the heart chambers and covers the valves.

Fibrous Skeleton of the Heart

• The fibrous skeleton is composed of four dense connective tissue rings.
• These rings encircle and bind the heart valves, and merge with the interventricular septum.
• It acts as a structural foundation for the heart valves.
• It prevents the stretching of valves as blood flows.
• It serves as a point of attachment for bundles of cardiac muscles and acts as an electrical insulator between the atria and ventricles.